Design and assisting system and method using electromagnetic position

Abstract

A design assisting system is constructed as a CAD (computer-aided design) system for assisting in designing printed-circuit boards or other electronic devices. The system makes it possible to design layouts for reducing an unwanted electromagnetic radiation due to a common-mode current. The system has a first tool for converting at least a set of an electronic device, an interconnection, and a ground plane from layout information of a circuit board into a model for analyzing an electromagnetic field, a second tool for specifying a frequency and calculating a magnetic field intensity distribution near the ground plane using the model, and a third tool for superposing the calculated magnetic field intensity distribution and the position of the interconnection, determining whether a position where a magnetic field or a current is strong and the position of the interconnection are close to each other or not, and outputting a determined result.

What is claimed is:  
     
       1. A design assisting system comprising: 
       means for converting at least a set of an electronic device, an interconnection, and a ground plane from layout information of a circuit board into a model for analyzing an electromagnetic field;  
       means for specifying a frequency and calculating a magnetic field intensity distribution near the ground plane using said model at the specified frequency; and  
       means for superposing the calculated magnetic field intensity distribution and a position of said interconnection, determining whether a position where a magnetic field or a current is strong and the position of said interconnection are close to each other or not, and outputting a determined result.  
     
     
       2. A design assisting system according to  claim 1 , further comprising: 
       means for changing the layout information of the circuit board.  
     
     
       3. A design assisting system according to  claim 2 , further comprising: 
       means for holding information above possible layout changes as a database.  
     
     
       4. A design assisting system according to  claim 1 , wherein said model of the electronic device comprises a metal wire and a voltage source, and said voltage source is disposed parallel to said ground plane. 
     
     
       5. A design assisting system comprising: 
       means for converting at least a set of an electronic device, an interconnection, and a ground plane from layout information of a circuit board into a model for analyzing an electromagnetic field;  
       means for entering an assumed position where a cable is connected;  
       means for specifying a frequency and calculating an electric field intensity distribution near the ground plane using said model; and  
       means for determining whether a position where an electric field is strong and said assumed position are in agreement with each other or not, and outputting a determined result.  
     
     
       6. A design assisting system according to  claim 5 , further comprising: 
       means for changing the layout information of the circuit board.  
     
     
       7. A design assisting system according to  claim 6 , further comprising: 
       means for holding information above possible layout changes as a database.  
     
     
       8. A design assisting system according to  claim 5 , wherein said model of the electronic device comprises a metal wire and a voltage source, and said voltage source is disposed parallel to said ground plane. 
     
     
       9. A design assisting system comprising: 
       means for converting at least a set of an electronic device, an interconnection, and a ground plane from layout information of a circuit board into a model for analyzing an electromagnetic field;  
       means for specifying a frequency and calculating an electric field intensity distribution near the ground plane using said model; and  
       means for finding a position whether an electric field is weak as a position suitable for cable connection, and outputting the position.  
     
     
       10. A design assisting system according to  claim 9 , further comprising: 
       means for changing the layout information of the circuit board.  
     
     
       11. A design assisting system according to  claim 10 , further comprising: 
       means for holding information above possible layout changes as a database.  
     
     
       12. A design assisting system according to  claim 9 , wherein said model of the electronic device comprises a metal wire and a voltage source, and said voltage source is disposed parallel to said ground plane. 
     
     
       13. A design assisting method comprising the steps of: 
       converting at least a set of an electronic device, an interconnection, and a ground plane from layout information of a circuit board into a model for analyzing an electromagnetic field;  
       specifying a frequency;  
       calculating a magnetic field intensity distribution near the ground plane using said model at the specified frequency;  
       superposing the calculated magnetic field intensity distribution and a position of said interconnection thereby to determine whether a position where a magnetic field or a current is strong and the position of said interconnection are close to each other or not; and  
       outputting a determined result.  
     
     
       14. A design assisting method according to  claim 13 , wherein said model of the electronic device comprises a metal wire and a voltage source, and said voltage source is disposed parallel to said ground plane. 
     
     
       15. A design assisting method according to  claim 14 , wherein a value of said voltage source is extracted from a model of the electronic device for a circuit simulator. 
     
     
       16. A design assisting method according to  claim 14 , wherein a value of said voltage source is determined based on a measured result of at least one selected from a group consisting of a voltage between terminals of said electronic device, a current at a terminal of said electronic device, an electric field near said electronic device, and a magnetic field near said electronic device. 
     
     
       17. A design assisting method comprising the steps of: 
       converting at least a set of an electronic device, an interconnection, and a ground plane from layout information of a circuit board into a model for analyzing an electromagnetic field;  
       specifying a frequency;  
       calculating a magnetic field intensity distribution near the ground plane using said model at the specified frequency; and  
       superposing the calculated magnetic field intensity distribution and a position of said interconnection, and determining whether a position where a magnetic field is strong and the position of said interconnection are close to each other or not; and  
       if the position where a magnetic field is strong and the position of said interconnection are close to each other, changing a layout of said circuit board, and effecting again said step of calculating and said step of superposing and determining.  
     
     
       18. A design assisting method according to  claim 17 , wherein said step of changing comprises the step of changing the layout of said circuit board using a database of possible layout changes. 
     
     
       19. A design assisting method comprising the steps of: 
       converting at least a set of an electronic device, an interconnection, and a ground plane from layout information of a circuit board into a model for analyzing an electromagnetic field;  
       entering an assumed position where a cable is connected;  
       specifying a frequency;  
       calculating an electric field intensity distribution near the ground plane using said model at the specified frequency;  
       determining whether a position where an electric field is strong and said assumed position are in agreement with each other or not; and  
       outputting a determined result.  
     
     
       20. A design assisting method according to  claim 19 , wherein said model of the electronic device comprises a metal wire and a voltage source, and said voltage source is disposed parallel to said ground plane. 
     
     
       21. A design assisting method according to  claim 20 , wherein a value of said voltage source is extracted from a model of the electronic device for a circuit simulator. 
     
     
       22. A design assisting method according to  claim 20 , wherein a value of said voltage source is determined based on a measured result of at least one selected from a group consisting of a voltage between terminals of said electronic device, a current at a terminal of said electronic device, an electric field near said electronic device, and a magnetic field near said electronic device. 
     
     
       23. A design assisting method comprising the steps of: 
       converting at least a set of an electronic device, an interconnection, and a ground plane from layout information of a circuit board into a model for analyzing an electromagnetic field;  
       entering an assumed position where a cable is connected;  
       specifying a frequency;  
       calculating an electric field intensity distribution near the ground plane using said model at the specified frequency;  
       determining whether a position where an electric field is strong and said assumed position are in agreement with each other or not;  
       if the position where an electric field is strong and said assumed position are in agreement with each other, changing a layout of said circuit board, and effecting again said step of calculating and said step of determining; and  
       outputting a determined result.  
     
     
       24. A design assisting method according to  claim 23 , wherein said step of changing comprises the step of changing the layout of said circuit board using a database of possible layout changes. 
     
     
       25. A design assisting method comprising the steps of: 
       converting at least a set of an electronic device, an interconnection, and a ground plane from layout information of a circuit board into a model for analyzing an electromagnetic field;  
       specifying a frequency;  
       calculating an electric field intensity distribution near the ground plane using said model at the specified frequency; and  
       finding a position whether an electric field is weak as a position suitable for cable connection based on said electric field intensity distribution.  
     
     
       26. A design assisting method according to  claim 25 , wherein said model of the electronic device comprises a metal wire and a voltage source, and said voltage source is disposed parallel to said ground plane. 
     
     
       27. A design assisting method according to  claim 26 , wherein a value of said voltage source is extracted from a model of the electronic device for a circuit simulator. 
     
     
       28. A design assisting method according to  claim 26 , wherein a value of said voltage source is determined based on a measured result of at least one selected from a group consisting of a voltage between terminals of said electronic device, a current at a terminal of said electronic device, an electric field near said electronic device, and a magnetic field near said electronic device. 
     
     
       29. A recording medium readable by a computer and storing a program which enables said computer to perform a process comprising the steps of: 
       converting at least a set of an electronic device, an interconnection, and a ground plane from layout information of a circuit board into a model for analyzing an electromagnetic field;  
       specifying a frequency;  
       calculating an electric field intensity distribution near the ground plane using said model at the specified frequency;  
       superposing the calculated magnetic field intensity distribution and the position of said interconnection thereby to determine whether a position where a magnetic field or a current is strong and the position of said interconnection are close to each other or not; and  
       outputting a determined result.  
     
     
       30. A recording medium readable by a computer and storing a program which enables said computer to perform a process comprising the steps of: 
       converting at least a set of an electronic device, an interconnection, and a ground plane from layout information of a circuit board into a model for analyzing an electromagnetic field;  
       entering an assumed position where a cable is connected;  
       specifying a frequency;  
       calculating an electric field intensity distribution near the ground plane using said model at the specified frequency;  
       determining whether a position where an electric field is strong and said assumed position are in agreement with each other or not; and  
       outputting a determined result.  
     
     
       31. A recording medium readable by a computer and storing a program which enables said computer to perform a process comprising the steps of: 
       converting at least a set of an electronic device, an interconnection, and a ground plane from layout information of a circuit board into a model for analyzing an electromagnetic field;  
       specifying a frequency;  
       calculating an electric field intensity distribution near the ground plane using said model at the specified frequency; and  
       finding a position whether an electric field is weak as a position suitable for cable connection based on said electric field intensity distribution.